You gain control by giving control. It's like a bank account. You make deposits by giving students choices in the areas you are willing to compromise. You withdraw from the account when you tell them to do something and they don't get a choice. For example, you ask if they would rather work on diddles or accents next. Later, when you are telling them you want them to play their accents a specific way, they accept your request because they feel respected. Once I started treating my kids this way--especially section leaders and seniors--I saw a huge difference in the way they responded to my requests and their overall rehearsal attitude.

Examples:

"Do you want to practice that again with or without the metronome?"
"Do you want to do that just marching again or add the music back in?"
"Do you want to repeat it at that tempo or move up to the next tempo?"

These are usually decisions that I can live with either way, as long as the end result is the kids playing the part better. Not only do they feel like they have more control. They often know better than me what is going to help them perform a part better. 9 times out of 10, they know exactly what they want immediately after I ask the question, and they are thrilled that we are rehearsing it in the way that helps them the most.

i have never seen them but that is just my opinion.